Diesel-electric engine control



Jan. 31, 1939. o scHLAEPFl-:R 2,145,511

DIESEL-ELECTRIC ENGINE CONTROL Filed Aug. ll, 1936 2 Sheets-Sheet l Jan, 31, 1939. K o SCHLAEPFER I 2,145,611

DIESEL-ELECTRIC ENGINE CONTROL Filed Aug. ll; 1956 2 Sheets-Sheet 2 ATTORN EY5 Patented Jan. 31, 1939 UNITED STATES PATENT OFFICE Oskar Schlaepfer, Winterthur, Switzerland, assignor to Sulzer Freres, Societe Anonyme, Winterthur, Switzerland Application August 11, 1936, Serial No. 95,358 In Switzerland August 12, 1935 10 Claims.

The present invention relates to a regulating device for a combustion engine driving an electric generator, particularly for vehicles, which regulates the supply of fuel to the engine as well as the excitation of the generator in dependence on the engine load.

According to the invention a device is provided which influences the regulation of the fuel supply during the regulation of the excitation in such a way that the increase of the fuel supply beyond an adjustable limit amount is prevented. The device can take the form of a movable stop which prevents the adjustment oi' the fuel supply regulator to an amount exceeding the limit amount. Furthermore, the same speed-controlled governor may regulate the fuel supply and the excitation of the generator, and between this governor and the device regulating the fuel supply av exible coupling may be provided.

It is known to regulate the excitation of the generator of a vehicle driven through electric transmission by a combustion engine, by aid of a governor driven by the combustion engine in such a way that the power delivered by the combustion engine remains constant. In known regulating devices, the engine governor which regulates the fue] is used for this purpose. Consequently, un'til the excitation of the generator is diminished to a sufficient extent, considerably more fuel may be supplied to the combustion engine than the amount corresponding to the full load output. Especially when the engine is switched over from one speed to a higher speed, an extraordinary increase of the amount of fuel supplied occurs, because on the sudden loading of the governor springs the setting for the highest possible amount of fuel is effected. From this there results poor combustion accompanied by heavy smoke, a disadvantage which is avoided by this invention.

In the drawings, practical embodiments of the invention are shown diagrammatically.

Fig. 1 shows a combustion engine coupled to an electric generator, which is operated at constant speed, and rhas a control device by means of which three different limit amounts for the fuel supply can be set.

Fig. 2 shows a regulating device for a combustion engine with three operating speeds, a special limit amount being set for each speed.

In Fig, 3 is shown a modification of the controller drum of Fig. 2.

In Figure 4 is a view of a modified form of mechanism for controlling the setting of the fuel 65 limiting device.

(CI. 29o- 17) Fig. 5 shows in detail a switch-controlled blocking device in association with a servomotor.

Referring to Fig. 1, the combustion engine drives a--main generator 2, and an auxiliary generator 4. The latter, which also can have a sepa- 5 rate drive, serves among other things for the excitation of the main generator 2, of which the output circuit is connected at 3. The excitation is varied by means of the regulating resistance 5. The governor 8 driven by the engine I through l0 the shaft 1 serves to regulate the supply'of fuel to the engine as well as to regulate the excitation f of the generator 2 in dependence on the load of the engine. The sleeve 9 of the governor 3 actuates the lever I0, which swings on the fixed l5 fulcrum I2 and is connected to the rod I3. 0n one end of the rod I3 is connected the control valve' I4 of the servomotor piston I5, controlling the pressure-oil feed channel I6 and the pressureoil discharge channels I1 and I1', for the piston 20 I5. The other end of the rod I3 is spring-coupled to the rack 22 by a coupling comprising a spring 20 and a spring plate 2I enclosed in a casing I9. Movement of the rack 22 regulates the fuel injection pump 23, the pistons 24 of which are 25 driven by the shaft 1 through cams 25.

The pistons 24 are provided with spirally formed control edges so that on turning each of the pistons around its longitudinal axis the degree of suction is changed and the amount of fuel de- 30 livered and injected is regulated in known manner. All of the pistons 24 are turned by the rack 22, which engages in teeth provided on the bushings 26, each being associated with a piston 24.

During the regulation of the excitation, the 35 regulation of the fuel supply is influenced by a device which is formed as a controllably movable stop which prevents the increase of the supply of fuel beyond an adjustable limit amount. 'Ihe stop comprises bent lever 21 which limits the 40 travel of the rack 22 towards the left. When the drum switch 33 is cut out, the magnets 30 and 3| are without current and the solenoid armature 32 fails to pull on the bent lever 21, so that the spring 28 draws it out against the fixed pin 29.

The mode of operation of the regulating device is as follows: The stop comprising the vertical arm of the angle lever 21 permits, in the position shown in the drawings, a displacement of the rack 22 toward the left up to the limit position (III) 50 The magnets 30 and 3| are without current, because the drum switch 33 is in the position M3.

In the limit position (III) the rack 22 is adjusted for the delivery of the greatest possible amount of fuel by the fuel pump 23, which, in this example, corresponds to the full load fuel capacity and full load torque of the engine I. The rod I3 is so adjusted that in the central or shut-olf position, as shown in the drawings, ofthe slide valve I4, which corresponds to the position of the governor when the output of the engine is to be kept constant, the rack 22 strikes against the stop 21 and the spring plate 2| rests on the left end of the casing I9. lIf now the load on the engine falls, the generator current decreases,fthe speed increases and the governor sleeve 9 moves towards the right. As a consequence the spring member I9, 2| pulls the rack 22 also towards the right, and the amount of fuel injected is diminished tov an extent corresponding to the displacementof the rack. Simultaneously the governor sleeve `pushes the control valve I4 towards the right'. 'Conse' quently pressure oil enters into the cylinderr chamber at the right of thev piston |5 which is displaced towards the left causing the lever |8 to cut out steps of the resistance 5, and increasing the excitation of the generator 2. This setting of the excitation remains until the load 'on the engine I has againincreased to such an extent that the governor 8 has returned the valve I4 to Ithe central or shut-oil position, and the rack 22 to the position for full load pump capacity.

, If now for any reason the load on the engine I increases, then the speed drops and the governor sleeve 9 moves towardsA the left, in the direction to increase the amount of fuel delivered by the pump23. Such an increase, however, does not occur, because they Araclr 22 is prevented from shifting towards the left by the stop 21, so that the amount of fuel remains unchanged. Merely the casing 4,I 9 is released from the spring plate 2|, and an unimpeded valve adjustment of the servomotor I4, I5 by the governor is possible. Hence, ythe slide valve I4 moves with the governor sleeve 9 towards the left, and pressure oil enters at the left of the piston I5 into the servomotor cylinder. .As a consequence the piston I5 causes the arm I8 to cut in steps of the resistance 5, and the ex- .'citation of the generator 2 is decreased until the load on engine corresponding to the output to be kept constant, is again reached.V Then the lgovernor 8 moves back into the initial position,

the slide valve I4 Amoves into the neutral position, and casing I9 again rests onthe spring plate 2|. 'Ihis control thus operates without the disadvantages resulting from a sudden injection of excess Ifuel.

In order to decrease the adjustment determining Athe limit amount of fuel to be supplied, the drum switch 33 is movedfrom the position M3 into the position Mz. Thereby the magnet 30 receives current and attracts the solenoid armature 32 so that the stop 21 is moved toward the right and the limit position (II) for the rack 22 ls set. This lifts the spring plate 2| from the casing I9,V whereby the governor 8 is not at first influenced, but only the diminished supply of fuel corresponding to the limit position II is adjusted. As no change has taken place for the time being in the load on the engine I, but as its torque be- `comes smaller, its speed drops. The rod |3 moves iowards the left and, as above described, the excitation of the generator 2 is diminished and the load reduced. The load is reduced until the original speed is again reached and thereby brought to a second value corresponding to the torque setting M2, which value the engine can now deliver at the original speed, but with the diminished amount of fuel. If the load rises beyond thissecond value the resultagaln is that during the regulating operation for Y changing the excitation of the generator 2 the supply of fuel cannot be set above the limit amount determined by the limit position (II) When the drum switch 33 is in the position M1 the magnet 3| also receives current so that both magnets attract the armature 32, and this holds the stop 21 fast in the limit position (I) for the rack 22, so that the fuel pump capacity and consequently the torque of the motor is reduced to the value corresponding to setting M1 lying below the torque resulting from setting M2.

If it is desired to retard the movement of the Y stop 21 between the limit positions I-II-III so as to prevent large fluctuation in the speed of the internal combustion engine while changes in the excitation of the generator 2 are taking place, it can be accomplished by the mechanism shown in Fig. 4.- The rod 32 no longer acts directly on the stop 21, but there is inserted the oil channel 41. If the coils 3D and 3| receive current, then rst of all the collar 48 is raised by the rod 32 thereby compressing spring 49. The retardation in the operation of the stop 21 is brought about by the constriction 50. The iow ofthe fluid through this constriction from the top to the bottom of the hollow piston 5| is retarded, and piston 5| is slowly forced upwardsuntil the collar 48 lies against the bottom of the hollow piston 5|. The actuating rod for the stop 21 being connected to the bottom of piston 5|, the stop 21 is moved slowly with the piston.

In aninternal combustion engine installation for a vehicle (for example a locomotive) according to Fig. 2, the generator 2 feeds the traction motors 6. The generator 2 has self-*excitation and separate excitation by the auxiliary exciter generator 4. The variation of the separate excitation takes place in the same way as in Fig. l'. The governor 34 has three springs 35, 36 and 36' which, by means of the pistons 31 and 38, are compressed or releasedy in such a way that the engine can be operated at three dii'lerentv constant speeds.

By turning the drum switch 46 from the position M1 to theposition M2, electromagnet 44 is energized and the valve 4| opens the compressed air supply ,from the pipe 42, which is supplied by any suitable source of compressed air, to the piston 31. Thereby the piston moves down to the stop 39 and compressesthespring 35, carrying with it piston 38. Additionally, spring 36` comes into contact with the piston 38. If the engine I operates at the lowest speed nl, with the pistons 31 and 38 in the positions shown in Flg. 2, then by the lowering of the piston 31 to the stop 39 the speed is increased to a'middle value nz.

If now in the position Ma, in Aaddition to magnet 44, the magnet 45 also receives `current so that the valve 40 opens ythe compressed air supply to the piston 38, then the latter goes down a `further distance, detaching itself from the lower edge of the piston 31r and going down to the stop 39. Thereby the spring 36 is compressed still further and the spring 38 is brought into action. The

engine then runs at the highest speed nz.

The switch 46 which serves to set the diiferent operating speeds n1, m and n3, also closes the circuit for the magnets 3| and 30 and `consequently determines the settings of the limit amounts of the fuel supply.' A limit amount is provided for each speed. This yields the ad? vantage that on every change of speed, the change of speed is effected in veryshort time .byv sudden increase or diminution of the correct amount of fuel. By means of a blocking device controlled from the switch 46, the piston I5, for example, can be held in its upper position with the whole resistance 5 cut in, as long as the switch 46 is in the neutral position. The purpose of this is to prevent large current surges at starting.' A suitable blocking device for this purpose is illustrated in Fig. 5 in the formv of a double switch cock 52 built into the pressure medium supplyline I6 and abduction conduit I1 of the control slide valve I4. The slide valve I3 which, as in Figs. 1 and 2, is connected withthe regulator 9,` is sealed of by the stulng box 53. -In the zero position of the switch 46, the armature 54 is drawn into the coil 56 counter to the action of spring 55 so that the cock 52 is shifted into the position indicated by II in which the connecting nipple 51 of the pressure oil feed line is connected with the conduit I1. In consequence thereof, the pressure oil passes under the piston I5 and lifts it to the uppermost end position so that the full resistance 5 is switched in. At the same time, the conduit I6 is connected with the nipple 56 so that all the pressure oil above the piston I5 is allowed to drain ofi' freely. On turning the switch 46 from the zero position to any one of the operative positions, the coil 56 becomes deenergized and spring 55 pulls the armature downwardly. Cock 52 is Withdrawn from the locking position II into the position I, in which the supply line nipple 51 is connected with conduit I6 and nipple I8 with conduit I1.

Such a blocking device can be dispensed with in the case of partial or exclusive self-excitation of the generator 2. In the case of partial self-excitation this must be so adjusted that, when the switch 46 is in the neutral position and the separate excitation cut out, it is not suftlcient to bring the generator 2 up to voltage. Itis then permissible, without damage to the generator, to cut in the full separate excitation when the switch 46 is in the position M1. The voltage of the main generator is then, however, built up. comparatively slowly so that the servomotor I4, I5 has time gradually to cut in a part oi' the resistance 5.

In Fig. 3 the contact segments of the drum switch 46 are so formed that not only three speeds, but, also for some of these speeds,'two different limit amounts for the supply of fuel can be adjusted.

By a different construction an additional graduation of the torques of the engine I and any desired coordination of the torques to the different speeds can be effected. The load on the engine can be so selected that the torque which corresponds to the maximum output to be kept constant by the governor, is adjusted by regulation of the fuel supply or of the rack 22 when the rack is in the limit position (II)- If then, by cutting out the magnets 30 and 3|, the stop 21 is in its extreme left position at the pin 29, the rack 22 does not rest on the stop 21 when the slide valve I4 is in the central position. On increase of the load on the engine it is true that then a somewhat increased amount of fuel will be present during the regulating operation for change of excitation of the generator 2, but this amount is so limited that a development of smoke is avoided or is kept within permissible limits. The increase of the amount of fuel is determined by the limit value which corresponds to the limit position (III). If in the limit position (II), for example, adjustment is made for full-load pump capacity, then a small overload corresponds to the limit position (III), whereas in the case of vjustment.

the limit position (I) adjustment is made .for a capacity smaller than for full load. *l

Inorder tov prevent alarge transitory drop of speed on` leesening the amount offuel, or in order to prevent'a correspondingl increase in speed on increase of the amount of fuel, the adjustment of the stop 21 or the rack 22 can be leffected under the influence of a retarding device,V such that this adjustment is started by operating the switch 33 or 46, but the speed of the movement of the stop 21 is limited by an oil "or air dampingpiston, or they like.-

Ifthe engine I is operated witl'isupercharging,

" that is, with increased air pressure,vor if there is involved a vehicle, which must travel at greatly varying altitudes, then the bent lever 21 can be adjusted in dependence on the pressure, thetemperature` or the humidity'of the surrounding air singly or in combination, and the increase of the supply of fuel beyond a determined limit amount can be prevented. The adjustment can be effected from the drivers cab and it can also be provided'in dependence on one of the values determining the condition of the air. In this case both adjustments can act on the same lever 21, or a special stop can be provided for each ad- In the latter case the limit amount of the fuel supply is determined by the stop which sets the smallest amount. Suitable apparatus for supercharging with increased air pressure or for melting various changes in air pressure due to changes in temperature or humidity is described and illustrated in United States Patent No. 1,975,624, dated June 2 0, 1933.

It will be observed that although the present invention has been describedv as applied to an internal combustion engine of the Diesel type, the principles of the invention may be applied to any type of engine wherewith similar control problems are experienced.

What I claim is:

1. In an internal combustion engine-electric power unit, the combination which comprises an internal combustion engine having fuel supply means, a main electric generator ldriven-by the engine, means for exciting the main generator, regulating apparatus operatively connecting the fuel supply means and the means for exciting the generator, whereby the quantity of fuel admitted to the engine and the excitation of the main generator are automatically influenced, and an adjustable limitation device in operative association with the fuel supply means and the regulating apparatus for limiting the increase of fuel under the action of the regulating device.

2. An internal combustion engine-electric power unit as claimed in claim 1, in which the limitation device comprises an adjustable stop which cooperates with a member operated by the regulating apparatus so as to control the quantity of fuel delivered to the engine.

3. An internal combustion engine-electric power unit as claimed in claim 1, in which the regulating apparatus comprises a governor driven by the engine which controls the excitation means and the fuel pump.

4. An internal combustion engine-electric power unit as claimed in claim 1, in which the limitation device is set by a manually operated control device through electiic means.

5. An internal combustion engine-electric power unit as claimed in claim 1, having means for altering the speed range within which the engine is to operate, in which a different maximum value or values, to which the'fuel can be increased by the automatic regulating apparatus, can be set by the limitation device foreach speed range.

6. An internal combustion engine-electric power unit as claimed in claim 1, in which a single control member or switch is provided which not only adjusts the limitation device but also determines the speed range Within which the engine is to operate.

7. An internal combustion engine-electric power unit as claimed in claim 1,111 which movement of the limitation device, during adjustment thereof, is retarded as by a dashpot or the like,

so as to avoid undesirable `speed fluctuations during regulation of the excitation of the main generator. n

8. An internal combustion engine-electric power unit as claimed in claim 1, which comprises a second limitation device'responsive to variations in atmospheric pressure in operative engagement with the fuel supply means, whereby the maximum value to which the fuel supplied to the engine can be increased is determined by either of the limitation devices whichever tends to set the lower fuel supply. .i

l 9. An internal combustion engine-electric pow- ,er unit as claimed in claim 1; in which the limitation device is set by a. manually operated control device through hydraulic means.

10. An internal combustion engine-electric power unit as claimed in claim 1, in which the limitation device is set by'a manually operated control device through mechanical means.

osKAR scLmAEPFER. 

